Notes on the BMW Diagnostic System
System Test
The system test makes it possible to activate all indicator/display instruments, lamps controlled directly by the instrument cluster and the display unit (LCD module). Internal data are also output via the display unit.
If the instrument cluster has been replaced, the exchange point is activated during the test.
Start System Test with BMW Diagnostic System
The system test can be started by the BMW diagnostic system ( *D* special functions).
Start System Test in Vehicle
Important! The system test can only be started from the vehicle when the BMW diagnostic system does not communicate (not connected) with the vehicle. The system test is immediately terminated if a BMW diagnostic system sets up data communication during the system test run.
- Switch off ignition (ignition switch in position 0).
- Press button for trip odometer reset and hold depressed.
- Switch ignition switch from position "0" to "1" (terminal R).
- Start system test, release button for trip odometer reset.
Test Procedure
The following are displayed in succession in the display unit (LCD module)
- BMW serial number
- Internal code number
- k-number
- Chassis number (without prefixed letters)
- Software number Revision Index.
All indicator/display instruments and the lamps controlled by the instrument cluster are then activated.
Notes on the BMW DIAGNOSTIC SYSTEM
The instrument cluster is capable of diagnostic procedures and is adapted to the various scope of functions by way of the coding data stored in a non-volatile data memory.
General
- Relevant safety codes and accident prevention regulations must be observed when carrying out all tests and work on the system.
- Battery charged.
- Fuses belonging to operation of the instrument cluster OK.
- Whenever possible, the battery should not be disconnected otherwise the stored defect codes in other control units would be deleted.
Test Equipment
The adapters recommended for troubleshooting are listed in Chapter-Pin Assignments.
Use only suitable test leads, terminals and probe tips.
*D* Defect Code Memory
The instrument cluster can store internal defect codes. The defect code memory is not cleared by removing the instrument cluster or disconnecting the battery.
*D* Defect Evaluation
The defect "EGS signal line faulty", "oil temperature sensor voltage not plausible" and "internal voltage supply faulty" can only be evaluated as of a software status >15.0.
The software status of the instrument cluster can be read out via *D* identification.
*D* Status Monitoring
The status of inputs and outputs of the instrument cluster can be indicated with the BMW diagnostic system. However, only a status which can be processed by the instrument cluster (scope of function) can be displayed. Indicator and warning lamps which are incorporated in the instrument cluster but which cannot be activated via the electronic circuitry of the instrument cluster cannot be checked by way of status monitoring.
In order to configure status monitoring as required, the individually selected inquiries can be displayed in a *D* status list.
The displayed status corresponds to the condition as seen by the instrument cluster. A defect can be quickly located by comparing the display on the BMW diagnostic system with the actual condition on the vehicle.
*D* Component Activation
Outputs can be activated with "component activation" while bypassing other logic operations. This makes it possible to quickly locate defects.
*D* Test Procedure
The test procedure can be used to check the inputs and outputs of the instrument cluster which are controlled and monitored by it. During the test procedure, the same status is indicated as during *D* status monitoring. However, the test procedure contains further accompanying information which is not contained in status monitoring.
*D* Special Functions System Test
The instrument cluster system test (also see functional description) can be triggered by the BMW diagnostic system.
*D* Special Functions Coding Data
By reading out several items of coding data, it is possible to perform a quick precheck as to whether the instrument cluster is suitable for the particular vehicle model. The complete scope of coding data is not displayed in this case.
Abbreviations
ABS Antilock brake system
ASC Automatic stability control
DME Digital engine electronics
DDE Digital diesel electronics
EGS Electronic transmission control
A Output
E Input
Poti Potentiometer
TD Engine speed signal (once per ignition)
ti Injection signal DME
TQ Injection quantity DDE